// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
#define CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_

#include <vector>

#include "base/macros.h"
#include "base/threading/non_thread_safe.h"
#include "content/common/content_export.h"

namespace content {

class NotificationObserver;
class NotificationSource;

// Aids in registering for notifications and ensures that all registered
// notifications are unregistered when the class is destroyed.
//
// The intended use is that you make a NotificationRegistrar member in your
// class and use it to register your notifications instead of going through the
// notification service directly. It will automatically unregister them for
// you.
class CONTENT_EXPORT NotificationRegistrar : NON_EXPORTED_BASE(public base::NonThreadSafe) {
public:
    // This class must not be derived from (we don't have a virtual destructor so
    // it won't work). Instead, use it as a member in your class.
    NotificationRegistrar();
    ~NotificationRegistrar();

    // Wrappers around NotificationService::[Add|Remove]Observer.
    void Add(NotificationObserver* observer,
        int type,
        const NotificationSource& source);
    void Remove(NotificationObserver* observer,
        int type,
        const NotificationSource& source);

    // Unregisters all notifications.
    void RemoveAll();

    // Returns true if no notifications are registered.
    bool IsEmpty() const;

    // Returns true if there is already a registered notification with the
    // specified details.
    bool IsRegistered(NotificationObserver* observer,
        int type,
        const NotificationSource& source);

private:
    struct Record;

    // We keep registered notifications in a simple vector. This means we'll do
    // brute-force searches when removing them individually, but individual
    // removal is uncommon, and there will typically only be a couple of
    // notifications anyway.
    typedef std::vector<Record> RecordVector;

    // Lists all notifications we're currently registered for.
    RecordVector registered_;

    DISALLOW_COPY_AND_ASSIGN(NotificationRegistrar);
};

} // namespace content

#endif // CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
